Heat transferring device

ABSTRACT

A device of the type known as heat pipe in which the heating means are inside the chamber and covered with a capillary structure in contact with the liquid to be evaporated. Applicable notably to isothermal oven. FIG. 1.

[ 1 May 28, 1974 [56] References Cited UNITED STATES PATENTS lnventors:Patrick Coville, Le Chesnay; Andre Laurencier, Courbevoie, both ofUnited States Patent Coville et al.

[ HEAT TRANSFERRING DEVICE Kodaira Basiulis..........

Scicchitano...

Kirkpatrick....

n n a m e b .w F 700 2 66777 99999 HHHH 62293 25970 77064 y 7433 2 605 3,5 3 33333 w e N 9 n o .l t a w r 0 C S my MN e C P n .1. m 50 F UY me en .m S S A .1 3 7 ABSTRACT 6 Claims, 6 Drawing Figures PrimaryExaminer-Albert W. Davis Attorney, Agent, or FirmFrank R. Trifari Adevice of the type known as heat pipe in which the heating means areinside the chamber and covered with a capillary structure in contactwith the liquid to be evaporated.

Applicable notably to isothermal oven. FIG. 1.

[22] Filed: May 24, 1972 [21] Appl. No.: 256,579

[30] Foreign Application Priority Data Feb. 25, 1972 France........

[51] Int.

[58] Field of Search 1 HEAT TRANSFERRING DEVICE The present inventionrelates to a heat transferring device of the type known under the nameof heat pipe. Said devices comprise an closed space containing a smallquantity of a liquid which is capable of evaporation.

Heating means applied locally to the said space produce the evaporationof a part of the liquid. A quantity of energy equivalent to the heat ofevaporation is taken along by the vapour throughout the length of thespace, the vapour condensing and giving off its heat of evaporation onthe surfaces which are at a temperature lower than that of the surfaceof evaporation. The condensed liquid is brought back, due to gravity orby capillarity, in the zone of evaporation. In order to ensure thereturn of the liquid the walls of the space may be covered on the insidewith a capillary structure in which the liquid is transported due tocapillary forces.

In the known devices, the heating means are always on the outside.Consequently these devices have relatively large dimensions, whilst theheating means can easily be damaged.

Furthermore, in devices in which the inner surface of the outer wall ofthe space is covered at least partly with capillary structuredifficulties are experienced in fixing said structure on a convexsurface. Several fixing methods have thus been proposed spot welding,soldering, holding by means ofa helical spring and so on without allthis permitting a simple and rapid mountmg.

It is the object of the invention to provide a heat transferring deviceof the kind described which remedies the above inconveniences.

According to the invention, the heating means are inside the space andcovered with a capillary structure in contact with the liquid to beevaporated.

In these conditions, the liquid is distributed through the capillarystructure throughout the surface of the heating element.

The return of the liquid toward the heating means may be augmented bycapillary communication means which connect the capillary structure tothe side wall of the space.

In other favourable embodiments:

at least'one capillary bridge is provided between the capillarystructure and the side wall of the space.

a rod covered with a capillary system is provided and extends to atleast a part of the length of the space, between the capillary structureand the side wall,

- in contact with these.

In a further favourable embodiment, a second capillary structure isprovided throughout the length of the space on at least a part of theside wall.

In a favourable embodiment constructed as an isothermal oven, in whichthe space is formed by an outer tube and an inner tube, the heatingelement is constituted by a screened cable which is wound around theinner tube.

The invention will be described with reference to the drawings.

In the devce shown in FIGS. 1, 2 and 3 the heating means 1 inside thespace A extends throughout the length or to a part of the length of thesaid space. It may be constituted by an electric heating element or byany other heating system known per se such as a gas burner, chemicalreaction, and so on, inside an envelope. The heating means 1 is coveredwith a capillary structure 3 in contact with the liqiid 4 to beevaporated in such manner as to permit the flow of said liquid in thestructure 3.

In order to facilitate the flow of the liquid towards the heatingelement, various arrangements may be used.

In FIG. 1, capillary bridges 5 are arranged at a distance from eachother connecting the capillary structure 3 to the side wall of thespace.

In FIG. 2, a rod of material compatible with the liquid and on which acapillary system 7 is present is arranged between the heating means Iand the side wall 2 in contact with these. As the rod 6 extendsthroughout the length of the space the return of the liquid towards theheating means will be best ensured.

In FIG. 3 the heating means 1 is eccentrically arranged, in contact withthe side wall. A second capillary structure 8 is also shown which isarranged (for example fixed by spotwelding) throughout the length of thespace on a part of the wall (for example, according to a generatrix).Said second capillary structure permits of using the device even if theheating means is located at a point at the top of the device.

FIGS. 4, 5 and 6 show various arrangements of the evaporation zone ofisothermal ovens for which the space A is defined by an outer tube 9 andan inner tube 10. The cross-section may be, for example, circular orrectangular.

In FIG. 4 the inner tube 10 is coaxially arranged with the outer tube 9and preferably covered by second capillary structure 11. A screenedheating cable 12 itself covered with capillary structure 13 is wound onat least a part of the inner tube 10. The connection to the outer tube 9is ensured by the capillary bridges 14 arranged according to ageneratrix which will preferably constitute the lower line of the.device when same is to function with a horizontal axis.

In FIG. 5 the connection between the heating cable 12 and the outer tube9 is obtained while interposing a rod 15, on which a second capillarysystem 15a is wound, against the inner tube 10.

In FIG. 6 the inner tube is arranged eccentrically in such manner thatthe cable 12 covered with the capillary structure 13 is held in contactwith the outer tube 9.

The operation of the device as described is well known and theadvantages of said devices are essentially due to simplification ofconstruction and to their reduced dimensions.

In general, the choice of the liquid, of the materials and of theheating elements will depend upon the operating temperature which it isdesirable to obtain, the quantity of liquid depending upon the capillarystructure and slightly exceeding the saturation of same. The capillarystructures are chosen and fixed according as the operation of the deviceis with, without, or against gravity, the examples given beingnon-limiting. In all these examples, the capillary structures are shownin the form of nets but it is to be understood that they may be replacedby any other type of structure currently used: wick, groove, and so on.

What is claimed is:

l. A heat transfer device comprising: an outer tube having an innersurface, an inner tube having length and an outer surface along saidlength, the inner tube situated within the outer tube, with an annularheattreatment space defined between said tubes, a quantity ofvaporizable liquid within said space, an energizable heat sourcecomprising a cable covered with a first capillary structure, a secondcapillary structure covering said outer surface of said inner tube, saidcable being wound around said inner tube and thereby holding said secondcapillary structure against said outer surface of said inner tube.

2. A device according to claim 1 further comprising connection meansconnecting said second capillary structure to said inner surface of saidouter tube.

3. A device according to claim 2 wherein said connection means comprisesa rod extending axially in said annular space.

4. A device according to claim 3 wherein said rod is situatedintermediate said second capillary structure and said cable such thatsaid first capillary structure on said cable is held in contact withsaid inner surface of said outer tube.

5. A device according to claim 4 further comprising a third capillarystructure covering said rod.

6. A device according to claim 1 wherein said inner tube is positionedeccentrically within said outer tube, whereby said first capillarystructure covering said heating means is held in contact with andbetween said second capillary structure covering said inner tube andsaid inner surface of said outer tube.

1. A heat transfer device comprising: an outer tube having an innersurface, an inner tube having length and an outer surface along saidlength, the inner tube situated within the outer tube, with an annularheat-treatment space defined between said tubes, a quantity ofvaporizable liquid within said space, an energizable heat sourcecomprising a cable covered with a first capillary structure, a secondcapillary structure covering said outer surface of said inner tube, saidcable being wound around said inner tube and thereby holding said secondcapillary structure against said outer surface of said inner tube.
 2. Adevice according to claim 1 further comprising connection meansconnecting said second capillary structure to said inner surface of saidouter tube.
 3. A device according to claim 2 wherein said connectionmeans comprises a rod extending axially in said annular space.
 4. Adevice according to claim 3 wherein said rod is situated intermediatesaid second capillary structure and said cable such that said firstcapillary structure on said cable is held in contact with said innersurface of said outer tube.
 5. A device according to claim 4 furthercomprising a third capillary structure covering said rod.
 6. A deviceaccording to claim 1 wherein said inner tube is positioned eccentricallywithin said outer tube, whereby said first capillary structure coveringsaid heating means is held in contact with and between said secondcapillary structure covering said inner tube and said inner surface ofsaid outer tube.